Davis is a decent player and in great form. He's capable of playing defensive midfield, central midfield, central attacking midfield, left midfield, right midfield. The thing Davis always brings in all these positions is high energy and a high level of tactical awareness. His decision making with and without the ball tends to be good (even if his execution of a decision on the ball isn't always good). I also like the fact he looks to pass the ball forward. These things are why he is so versatile.
When Clyne played right back for us (particularly under Pochettino) Davi often filled into the right back slot and never looked troubled when Clyne got caught forward. This leads me to believe he would be ok at right back. The fact he looks just as good at left midfield as right midfield I'd say he could also do a job at left back. And Having seen Gary Medel look a quality centre back in the world cup and Copa America I feel Davis would even be good at centre back. This sort of talk is arguably pointless, and ridiculous, as we obviously don't need him to play these three positions ever..but it's just an observation of how versatile he actually is. He's good enough on the ball, his decision making and tactical awareness is very good to play these positions in my opinion.
The one thing to improve has always been his abysmal finishing and heading. This is starting to improve, but he still needs to play a few more killer passes. The problem is when he is off the pace sometimes, or generally off form for a while, it is a huge problem for him and others if he isn't a goal threat at all. It means the opponent can focus more on our players that are capable of getting the ball in the net, or capable of providing an assist. I'm happy right now he's in red hot form on and off the ball, hopefully it continues.